Sorry I should learn to read properly, you are asking about the depth and not the opening !
In that case 7 inches will be fine but as Paul says it might mean you need to take some of the back bar out to make it fit, but not always, the unit below fit fine without removing that back bar and so did my Xtrons unit which is a depth of 169mm, or just under 7 inches so you should be fine
Below are some pictures of a fit I did with Devilish at a meet in Doncaster for another owner, we didnt have to take out the back bar but did have to build a platform to take the weight of the unit as most have to do if using the same type of units as they are heavy. On this occasion we also had to cut the top of the double din facia too as the unit was too big but when the eyebrow is fitted you cannot see it and in the end it becomes a tidy fit, plus you can also buy walnut covers for the facias if you want to match it with the rest of the central dash.
the silver metal bar on this picture is the oem one that can be removed if you have too, bit if not it can be used to bolt on the support bracket
had to cut the top off the double din facia
Of course you can always buy one of the units that were fitted in the Chinese equivalent MG7 and which is plug and play, depends on your budget thay are around Â£300, but no facia to buy and no support bracket to make, so its an option.